Ultrasound transmitting components, such as acoustic windows and lenses, for medical imaging systems are desired to comply with several requirements, such as providing: an optimal low loss acoustic wave transmission; chemical and mechanical barriers to protect the ultrasound array elements; electrical barrier to protect a patient from the electrically active transducer elements. In U.S. Pat. No. 4,699,150 polymethylpentene polymer (for example available from Mitsui Chemicals under trade name TPX) is used as a contact member, which is brought to contact with an object being examined and formed on the one surface of the ultrasound transducer. The polymethylpentene polymer is chosen due to its durability and low acoustic wave attenuation.
However, polymethylpentene based polymers used as a part of acoustic windows and lenses in the ultrasound imaging systems introduce image artifacts. Furthermore, polymethylpentene based polymers have an acoustic impedance of 1.7 MRayls or higher, which is too high for some of the medical ultrasound applications. There are alternative materials as for example: polyether/polyamide block copolymer which has low attenuation but low chemical compatibility, and filled silicone (silicon rubber) which has higher attenuation and fluid permeability issues.
Currently there is no available as acoustic windows material, which would meet most of the ultrasound system's requirements.